Analysis Of Uncertainty In Measuring Boundary Slip Using Atomic Force Microscope

It cannot be ignored that the boundary condition of fluid dynamics,that is,liquid border state is important in micro and nano scale.In recent a dozen years,the methods of measuring boundary slip came out one after the other.And atomic force microscopy is considered as the most accurate measurement method due to its nanometer sensitivity.However,the most of measurement methods including the method using atomic force microscopy lack comprehensive assessment of the measurement results uncertainty.In this study,atomic force microscope is used to measure boundary slip on smooth hydrophilic surfaces.And the process of measuring boundary slip and the data processing method based on a n?mber of previous experiments are s?mmarized.By analysing the factors which influence the entire process of measuring boundary slip,uncertainty evaluation method is presented based on Bessel method.After a series of experiments about measuring boundary slip on smooth hydrophilic surfaces,the factors which influence the boundary slip are validated and the uncertainty components are calculated.At last,establish a uncertainty evaluation system which is about measuring boundary slip using atomic force microscopy.In this study,several current methods of measuring boundary slip are introduced,and the advantages of using the atomic force microscope to measure boundary slip are analyzed.And the various factors that affect the slip measurement are s?mmarized.On this basis,the standard process of measuring boundary slip and the methods which is to eliminate the influence of the interference and deviation existing in the measuring process are proposed.and the application scope and conditions of this standard process are defined.This part is the foundation for uncertainty evaluation.It provides a research reference for the boundary slip experiments.In this study,the uncertainty components in the measurement process are analysed in four aspects including the zero point position of force curves,electrostatic force,Stokes force and the spring constant of probe.And the transfer models of each uncertainty component are analysed.Then the evaluation methods of uncertainty are put forward in three aspects which are data processing,measurement instr?ments and environmental conditions.Experiments of measuring boundary slip on smooth hydrophilic surfaces were arranged to collect enough error data about the process of measuring boundary slip.The relationship between electrostatic force and slip length is verified by the double speed method.The sources of error in the process of data processing are analysed,and the standard uncertainty of Stokes force and zero point position are calculated.